use current provider for gas price

src/blockchain/blockchain.js

@@ -132,7 +132,7 @@ class Blockchain {
   }
 
   determineGasPrice (cb) {
-    this.executionContext.web3().eth.getGasPrice((error, gasPrice) => {
+    this.getCurrentProvider().getGasPrice((error, gasPrice) => {
       const warnMessage = ' Please fix this issue before sending any transaction. '
       if (error) {
         return cb('Unable to retrieve the current network gas price.' + warnMessage + error)

src/blockchain/providers/injected.js

@@ -30,6 +30,10 @@ class InjectedProvider {
     })
   }
 
+  getGasPrice (cb) {
+    this.executionContext.web3().eth.getGasPrice(cb)
+  }
+
   signMessage (message, account, _passphrase, cb) {
     const hashedMsg = Web3.utils.sha3(message)
     try {

src/blockchain/providers/node.js

@@ -38,6 +38,10 @@ class NodeProvider {
     })
   }
 
+  getGasPrice (cb) {
+    this.executionContext.web3().eth.getGasPrice(cb)
+  }
+
   signMessage (message, account, passphrase, cb) {
     const hashedMsg = Web3.utils.sha3(message)
     try {

src/blockchain/providers/vm.js

@@ -72,6 +72,10 @@ class VMProvider {
     })
   }
 
+  getGasPrice (cb) {
+    this.executionContext.web3().eth.getGasPrice(cb)
+  }
+
   signMessage (message, account, _passphrase, cb) {
     const personalMsg = ethJSUtil.hashPersonalMessage(Buffer.from(message))
     const privKey = this.providers.vm.accounts[account].privateKey